KR102673252B1 - Magnetic field sensor with compensation for magnetic field sensing element placement - Google Patents

Abstract

Methods and devices are disclosed for a sensor system having a first magnetic field sensing element having first and second segments, wherein the first and second segments reduce sensitivity due to misalignment of the first and second segments. They are located at locations that generate magnetic field bias in opposing directions to reduce the magnetic field bias. A processing module is configured to receive the output of the magnetic field sensing element.

Description

Magnetic field sensor with compensation for magnetic field sensing element placement

The present invention relates to a magnetic field sensor with compensation for the placement of magnetic field sensing elements.

Magnetic sensors are widely used in modern systems to measure or detect physical parameters such as magnetic field strength, current, position, motion, orientation, etc. There are many different types of sensors for measuring magnetic fields and other parameters. However, these sensors suffer from various limitations, such as excessive size, insufficient sensitivity and/or dynamic range, cost, reliability and the like. Additionally, positional misalignment of magnetic field sensing elements may degrade sensor performance.

The present invention provides a method and device for misalignment compensation of a magnetic field sensing element according to example embodiments. In embodiments, the magnetic field sensor includes a single element, or a half or full bridge structure, with opposing magnetic field bias polarities to compensate for position misalignment along at least one axis. It includes a magnetic field sensing element having magnetic field sensing elements divided into segments that undergo. In embodiments, the magnetic field sensing elements are provided as GMR elements in a half bridge or bridge configuration. In the presence of a sensing element in positional misalignment with respect to the magnetic field, a first segment of the GMR element will have an increased or decreased sensitivity to the bias polarity, a second segment opposite the first segment will have a decreased or increased sensitivity, and It will have opposing bias polarities. The effect of misalignment is reduced due to compensation provided by the combination of the first and second segments comprising one of the magnetic field sensing elements.

In one aspect, a sensor system includes a first magnetic field sensing element having first and second segments, the first and second segments facing each other to reduce sensitivity due to misalignment of the first and second segments. It is located at locations that generate magnetic field bias in directions and includes a processing module that receives the output of the magnetic field sensing element.

The sensor system may further include one or more of the following features. The misalignment is determined from the center of the magnetic field generated by the magnet, the misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field, and as the misalignment increases, the first segment experiences a stronger magnetic field, the second segment experiences a weaker magnetic field, and the processing module combines signals from the first and second segments to reduce sensitivity due to misalignment of the first and second segments. configured to couple, the first magnetic field sensing element comprising a GMR separated into two parts, the first and second magnetic field sensing elements configured in a half-bridge configuration, and the third and fourth magnetic field sensing elements Further comprising: the first, second, third and fourth magnetic field sensing elements are configured in a bridge configuration, the third magnetic field sensing element includes fifth and sixth segments, and the fourth magnetic field sensing element includes The first magnetic field sensing element comprises seventh and eighth segments and/or the first magnetic field sensing element comprises TMR elements.

In another aspect, the method includes applying a first magnetic field sensing element having first and second segments, the first and second segments reducing sensitivity due to misalignment of the first and second segments. and applying a processing module to receive the output of the magnetic field sensing element, located at locations that generate magnetic field biases in opposing directions.

The method may further include one or more of the following features. The misalignment is determined from the center of the magnetic field generated by the magnet, the misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field, and as the misalignment increases, the first segment A segment experiences a stronger magnetic field, the second segment experiences a weaker magnetic field, and the processing module receives signals from the first and second segments to reduce sensitivity due to misalignment of the first and second segments. configured to combine, the first magnetic field sensing element comprising a GMR separated into two parts, the first and second magnetic field sensing elements configured in a half-bridge configuration, and the third and fourth magnetic field sensing elements further comprising applying the first, second, third and fourth magnetic field sensing elements, wherein the first, second, third and fourth magnetic field sensing elements are configured in a bridge configuration, the third magnetic field sensing element comprising fifth and sixth segments, and Four magnetic field sensing elements include seventh and eighth segments, wherein the first magnetic field sensing element includes GMR elements and/or the first magnetic field sensing element includes TMR elements.

In another aspect, a sensor system includes magnetic field sensing means having first and second segments, the first and second segments being opposed to reduce sensitivity due to misalignment of the first and second segments. It is located at positions that generate magnetic field bias in directions and includes processing means for receiving the output of the magnetic field sensing means. The misalignment is determined from the center of the magnetic field generated by the magnet. The misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field.

Not only the features of the present invention described above, but also the present invention itself can be understood in more detail from the description of the following drawings. In the attached drawings,
1 is a block diagram of a sensor with compensation for magnetic field sensing element position misalignment according to exemplary embodiments of the present invention;
1A is a schematic diagram of a sensor having a bridge configuration with compensation for magnetic field sensing element position misalignment according to exemplary embodiments of the invention;
2 shows an exemplary GMR element layer configuration that can form part of a sensor having GMR elements in a bridge configuration with compensation of GMR element position misalignment according to exemplary embodiments of the invention;
3A shows the magnet and magnetic vectors without magnetic field sensing element misalignment;
3B shows a magnet and magnetic vectors with magnetic field sensing element misalignment;
4A shows a portion of a sensor having magnetic field sensing elements in a bridge configuration with segments at opposing bias positions without misalignment according to exemplary embodiments of the invention;
Figure 4b shows the equivalent circuit for the sensor portion of Figure 4a;
Figure 4c shows a heat map of the magnetic field Hy (along the Y axis) generated by a magnet in the plane XY;
5 shows a portion of a sensor having magnetic field sensing elements having segments at opposing bias positions with misalignment according to exemplary embodiments of the invention;
6 is a flow diagram illustrating an example sequence of steps for providing magnetic field sensing elements having segments at opposing bias positions with misalignment in accordance with example embodiments of the invention;
Figure 7 is a schematic diagram of a portion of a sensor having magnetic field sensing elements with segments at positions relative to a magnet according to exemplary embodiments of the invention;
Figure 8 schematically shows a part of a sensor having magnetic field sensing elements, Figure 8a shows the circuit configuration of the left and right bridges formed by the magnetic field sensing elements of Figure 8, and Figure 8b shows the magnetic field sensing elements of Figure 8. Represents symmetrical and three-point bridges formed by,
Figure 9a shows a schematic diagram of a magnetic field sensor with magnetic field sensing elements and segments arranged in relation to the magnetic field of a magnet;
Figure 9b shows a schematic diagram of a magnetic field sensor having magnetic field sensing elements and segments dimensioned and/or spaced with respect to the magnetic field of a magnet;
Figure 9c shows a schematic diagram of a magnetic field sensor having magnetic field sensing elements and segments dimensioned and/or spaced with respect to the magnetic field of a magnet;
10 shows a schematic diagram of the bias exhibited by example magnetic field sensing segments;
10A shows a schematic diagram of the bias exhibited by example magnetic field sensing segments for a shape-controlled magnet;
11 shows exemplary magnet configurations for a magnetic field sensor;
Figure 12 is a schematic diagram of an example computer capable of performing at least a portion of the processing described herein.

1 is a circuit diagram illustrating an example of a magnetic field sensor 10 including a magnetic field sensing element 12 with bias misalignment compensation according to example embodiments of the present invention. In embodiments, the magnetic field sensing element 12 may be positioned relative to a magnet 13, for example. In embodiments, the magnetic field sensing element 12 senses, for example, a ferromagnetic target 14 causing changes in the magnetic field. A signal processing module 16 is coupled to the magnetic field sensing element 12 to process signals from the sensing element. An output module 20 is coupled to the signal processing module 16 to provide an output signal for a device containing the magnetic field sensor.

In one embodiment shown in Figure 1A, the magnetic field sensing element 12 of Figure 1 includes a GMR magnetic field sensor 110 in the form of a bridge. The bridge circuit 110 includes magnetic field sensing elements such as GMR elements 112, 114, 116, and 118 disposed on each branch of the bridge 110. As shown and described in more detail below, the GMR elements 112, 114, 116, 118 may be divided into two or more segments to provide misalignment compensation.

In the illustrated embodiment, one end of the GMR element 112 and one end of the GMR element 116 are commonly connected to a power supply terminal (V _cc ) through a node 120, and the GMR One end of element 114 and one end of the GMR element 118 are commonly connected to ground through node 122. The other end of the GMR element 112 and the other end of the GMR element 114 are connected to a node 124, and the other end of the GMR element 116 and the other end of the GMR element 118 are connected to a node ( 126).

In the illustrated embodiment, node 124 of the bridge circuit 110 is connected to a differential amplifier circuit 130. Additionally, node 126 is connected to the differential amplifier circuit 130. The first output of the differential amplifier circuit 130 is connected to the output module 140. In embodiments, Vcc may be used to compensate for gain variations of the GMR elements over process and temperature. It will be appreciated that the differential amplifier circuit 130 may include an offset trim to correct for GMR sensor mismatch and/or a sensitivity trim to adjust gain over temperature and process.

The magnetic field sensing planes of the GMR elements 112, 116 and 114, 118 respond to magnetic fields by corresponding resistance changes. GMR elements 112 and 118 have maximum and minimum resistances at positions that are phase shifted compared to that of GMR elements 114 and 116. This is due to the different pinning orientation of the magnetism and/or other components of the system being constructed. As a result, the voltages (mid-point voltages) at the nodes 124 and 126 of the bridge circuit 110 are also changed in a similar manner.

Magnetoresistance refers to the dependence of the electrical resistance of a sample on the strength of an external magnetic field, characterized as follows:

δ _H = [R(0)-R(H)]/R(0)

where R(H) is the resistance of the sample in the magnetic field (H), and R(0) corresponds to H=0. The term “giant magnetoresistance” indicates that the value δ _H for multilayer structures significantly exceeds the anisotropic magnetoresistance, which is within a few percent of its typical value.

Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance effect observed in thin film structures composed of alternating ferromagnetic and nonmagnetic conductive layers. This effect is observed as a significant change in electrical resistance depending on whether the magnetization of adjacent ferromagnetic layers is in a parallel or antiparallel arrangement. The overall resistance is relatively low for parallel configurations and relatively high for anti-parallel configurations. The magnetization direction can be controlled, for example, by applying an external magnetic field. This effect is based on the dependence of electron scattering on spin orientation. A bridge of four identical GMR devices is not sensitive to uniform magnetic fields, but responds when the magnetic field directions within neighboring arms of the bridge are antiparallel.

FIG. 2 illustrates a simplified GMR sensor 200 that may form part of the magnetic field sensor 10 of FIG. 1 according to one embodiment. In Figure 2, the GMR sensor 200 includes a pinned layer 210, a metal path 212 such as copper, and a free layer 214. The self-orientation of the pin layer 210 is fixed. The magnetic orientation of the free layer 214 may be through anisotropy or an arrangement selected by the optional second pinning layer 220 shown, which respectively provides a pinning field (H _an ) 242 (FIG. 2). is maintained. The magnetic orientation of the free layer 214 rotates 242 based on the applied magnetic field.

As shown, anisotropy can be utilized to create a 90° zero applied magnetic field orientation 240 of the free layer 220, or a 90° zero applied magnetic field orientation 240. ) may be provided as the second fin layer 220 at an angle of 90° with respect to the fin layer.

The sensitivity of the GMR (Giant Magnetoresistance) element used in a back bias environment depends on the magnetic bias (either internal or external to the GMR structure). The bias induced by the magnet is typically not uniform, and since the GMR sensitivity varies with the position of the GMR relative to the magnet, placement tolerance can be a major factor in the accuracy of the sensor.

Embodiments of the present invention divide the GMR structure into at least two segments, position the first GMR segment in a region with a positive bias, and position the second GMR segment in a symmetric region with an opposing bias to Provides reduction of the effect of sensing element misalignment with respect to the magnet on sensitivity. The zones, at least one of which is aligned with the surface of the magnet, are defined by one or more axes passing through the center of the magnet. In a configuration without misalignment, the first and second segments in opposing zones of bias will have the same magnitude of bias and therefore the same sensitivity. In case of misalignment of the sensing element with respect to the magnetic field, the first segment will increase/decrease its bias with a resultant increase/decrease in sensitivity, and the second segment will increase/decrease its bias, as explained in more detail below. It will have opposing behavior with increasing/decreasing bias with resulting increase/decrease. The first and second GMR segments attempt to compensate each other for sensitivity in the presence of misalignment of the GMR structure with respect to the bias magnet.

3A and 3B show bias changes for magnet 300. Position determination is described using x, y and z coordinates as shown. Figure 3a shows a configuration with a magnetic field sensing element that can be provided as a GMR element centered about the Y axis, where the magnetic field sensing elements have first and second segments experiencing opposing magnetic field polarities. The magnet 300 generates a bias on the Y-axis that is symmetrical to the bias on the X-axis. For simplicity purposes, zero coordinate 302 lies at the center of the magnet 300. Since the point at coordinates "x1, y1" is equal to and has a bias on the opposite Y axis as the point at coordinates "x1, -y1", the magnetic vector B1 is equal to and opposite the magnetic vector B2. . As can be seen, the magnetic vectors B1 and B2 have the same length/size and are located at the same distance from the X-axis. The first segment may be located at “x1, y1”, and the second segment may be located at “x1, -y1”. In embodiments, the sensing element is centered relative to the magnet.

Figure 3b shows magnetic field sensing element misalignment along the Y axis. The Y-axis size increases (in absolute value) as it moves from the (x, y) center of the magnet in the Y direction. Due to the misalignment, the magnetic vectors B3 and B4 have the same distance between them, but are offset in the Y direction relative to the magnetic vectors Bl and B2, which corresponds to no Y-axis misalignment. do. The magnetic vector B3 is located further away from the center of the magnet than B1 and has a stronger bias on the Y-axis than B1. The magnetic vector B4 is located closer to the center of the magnet compared to B2 and has a weaker bias on the Y axis compared to B2. In embodiments, the center is defined as the intersection of the magnet's axes of symmetry, as shown in Figure 7. The fact that it has a zero magnetic field at the center is a result of symmetry. Additionally, when the magnet magnetization is tilted, a zero magnetic field at the center no longer exists.

It will be understood that the GMR sensing element changes its resistance (R) in approximately proportion to the cosine of the magnetic vector according to the following equation.

R ~ Hx/sqrt(Hx^2＋Hy^2)

Here, Hx is the magnetic field on the X-axis, and Hy is the magnetic field on the Y-axis. Hx is usually the 'useful' magnetic field. In the illustrated embodiment, the target moves along the X-axis (from left to right or vice versa).

From this fact it will be understood that a single GMR structure is relatively insensitive to its position on the Y axis because its components on the Y axis are changing accordingly. Misalignment on the Y axis between the GMR structure and the magnet shifts the GMR magnetic vector from Bl to B3, which can significantly affect the response of the GMR.

In embodiments, the GMR elements are segmented and positioned to compensate for misalignment. For example, the first segment may be located at coordinates “x1, y1” and the second segment may be located at coordinates “x1, -y1”. If there is no misalignment, the first and second GMR segments will have substantially the same response because they have the same orientation from X and therefore the same Hy magnetic field.

It will be appreciated that the Hx magnetic field is assumed to be similar in amplitude due to the same distance from the Y axis, or due to the use of magnets with a uniform magnetic field in the X axis. In case of misalignment of the magnet to the GMR structure in the Y direction, both segments will move either upward or downward. In this case, as the first segment increases its bias on the Y axis, the second segment decreases its bias on the Y axis to compensate for the first segment to a first approximation, or vice versa. do.

As previously indicated, the GMR element arranged to generate the magnetic field vector B3 reduces its sensitivity due to stronger magnetic fields on the Y-axis, but the GMR element arranged to generate the magnetic field vector B4 A weaker magnetic field on the Y axis increases its sensitivity. The two sensitivities tend to compensate for each other to minimize the effects of Y-axis misalignment.

FIG. 4A shows an example system 400 with a GMR bridge 402 positioned relative to a magnet 404 without misalignment. The magnetic field in the Z-axis direction is shown by arrow 406. Note that the magnetic field in the X direction is not shown. The first GMR element 408 includes a first segment 408a and a second segment 408b, the second GMR element 410 includes a third segment 410a and a fourth segment 410b, The third GMR element 412 includes a fifth segment 412a and a sixth segment 412b, and the fourth GMR element 414 includes a seventh segment 414a and an eighth segment 414b.

When compared to a conventional GMR bridge, the first GMR element 408 has the first and second segments 408a and 408b having substantially equal bias magnitudes with opposite polarities because there is no Y-axis misalignment. It is divided into Similarly, the segments of the second, third and fourth GMR elements experience substantially the same bias of opposite polarity.

In the illustrated embodiment, a voltage source (V _CC ) may be connected to the first segment 408a of the first GMR element 408a and the fifth segment 412a of the third GMR element and may be connected to an electrical ground (GND). ) may be connected to the seventh segment 414a of the fourth GMR element 414 and the fourth segment 410b of the second GMR element.

Figure 4b shows an equivalent electrical circuit showing the segment's connections to V _CC and GND. It will be appreciated that V _CC and GND can be connected to the GMR elements in a variety of configurations to meet the needs of specific applications.

4C shows an exemplary thermal map of the magnetic field Hy (along the Y axis) generated by a magnet with exemplary dimensions (X; Y; Z) = (5; 4; 3) mm in the XY plane at a distance of 2.5 mm from the magnet. Indicates a heat map. The rectangle represents the position of the magnet in the XY plane. The units are mm for X and Y and Oersted for magnetic fields. At the center, the map shows the Hy magnetic field gradient along the Y axis, with a negative magnetic field for Y<0 and a positive magnetic field for Y>0. The Hy magnetic field is relatively constant across the X-axis.

5 shows an example system 500 with a GMR bridge 502 positioned relative to a magnet 504 in Y-axis sensing element/magnet misalignment. The magnetic field in the Z-axis direction is shown by arrow 506. The first GMR element 508 includes a first segment 508a and a second segment 508b, the second GMR element 510 includes a third segment 510a and a fourth segment 510b, The third GMR element 512 includes a fifth segment 512a and a sixth segment 512b, and the fourth GMR element 514 includes a seventh segment 514a and an eighth segment 514b.

As can be seen, the distances D1 and D2 from the X axis to the first segment 508a and to the second segment 508b of the first GMR element 508 are different. In embodiments, each segment of the second, third and fourth elements is also spaced at different distances from the X-axis.

Because the second segment 508b of the first GMR element 508 is closer to the center C of the magnet than the first segment 508a, the second segment has a higher relative magnetic field than the first segment. Has sensitivity. When the first and second segments 508a, 508b are electrically connected in series, the total sensitivity of the first GMR element includes the combined sensitivity of the first and second segments 508a, 508b. .

In one embodiment, the increased sensitivity of the second segment 508b of the first GMR element 508 is increased to a first approximation because δR = δHx/sqrt(Hx0 ² + Hy ² ). Compensates for the reduced sensitivity of segment 508a, where δR is the amplitude of the signal, δHx is the change in magnetic field along the X-axis that generates the signal, Hx0 is the static magnetic field along the It is a magnetic field. When Hy increases, the signal decreases, and when Hy decreases, the signal increases.

6 shows an example sequence of steps for providing misalignment compensation according to example embodiments. The steps of FIG. 6 may be understood in conjunction with the exemplary embodiment of FIG. 5 . At step 600, segments of the first magnetic field sensing element are placed at positions of opposing magnetic field bias provided by the magnet. In embodiments, the magnetic field sensing elements are configured as a bridge. In embodiments, the magnetic field sensing elements include GMR elements.

At step 602, segments of the second magnetic field sensing element are placed at positions of opposing magnetic field bias. At step 604, segments of the third magnetic field sensing element are placed at positions of opposing magnetic field bias. At step 606, segments of the fourth magnetic field sensing element are placed at positions of opposing magnetic field bias provided by the magnet. As described above, segments of the magnetic field sensing element at opposing bias positions compensate for positional misalignment of the elements with respect to the magnetic field that may be provided by the bias magnet.

Although example embodiments are shown and described with GMR elements, it will be understood that other types of MR elements may be used, such as TMR elements.

7 shows first and second bridges having three groups of GMR elements (left, center, right) with the GMR elements positioned relative to the magnets to eliminate sensitivity to common mode magnetic fields and alignment bias. Branch shows an exemplary embodiment of a back bias 'speed' sensor. The GMR elements experience opposing biases. The sensor provides speed and direction information of the target to first and second bridges having GMR elements located at different X positions as shown. Due to the symmetry of the sensor, a symmetrical bridge has the GMR elements experiencing the same bias when the die and the magnet are perfectly aligned. Accordingly, the sensor is not affected by stray fields when the die and magnet are perfectly aligned.

Figure 8 shows a sensor with GMR elements, and Figures 8a and 8b show alternative bridge configurations undergoing opposing biases. Figure 8 shows first and second GMR bridges each having four elements, where each element has first and second segments. Figure 8a shows the left bridge and right bridge for the bridges of the sensor of Figure 8. Output signals from the left and right bridges can be used to determine speed and direction information. In one embodiment, subtracting and summing the corals in the left and right bridges outputs speed and direction information. The GMR elements are written with the subscript l indicating the left, r indicating the right, and c indicating the center. Referring to Figure 8, the yokes (Ax and Cx) may be referred to as external, and the yoke (Bx) may be referred to as the central or internal yokes. From left to right in FIG. 8, the GMR elements can be listed as A _l , A _c , B _l , B _cl , B _cr , B _r , C _c and C _r . As can be seen in the left bridge of FIG. 8A , the GMR element A _l includes first and second segments A _la , A _lb , and the GMR element B _cl includes third and fourth segments contains elements (B _cla , B _clb ), and so on.

In this arrangement, the segments of the GMR elements do not experience exactly the same bias conditions. For example, the bias magnetic field that can be generated along the Z axis by a magnet (Figure 8) varies slightly between the inner and outer yokes. This creates a difference in the sensitivity of the elements, resulting in a comprehensive sensitivity to common mode magnetic fields.

FIG. 8B shows symmetrical and three point bridge configurations that may be useful for a back bias speed sensor. In one embodiment, the symmetric bridge of A _l , C _c , C _r and A _c may be referred to as a directional channel, and the three-point bridge may be referred to as a velocity channel. _{The yokes A}

In embodiments, the yokes should be arranged in pairs in a symmetrical manner with respect to the magnet. One yoke must be placed at position (+Yp), and the second yoke must be placed at Ym = -Yp (assuming Y = 0 as the center of the magnet). The spacing S (e.g. 2*Yp) is then chosen to be high enough so that the bias due to the magnet is large enough to ensure adequate compensation of misalignment along the Y axis and stray magnetic fields along the same axis, and the desensitivity The air gap is small enough to ensure that the signal is not attenuated too much. In embodiments, compensation for bias of the GMR and good tolerance for misalignment across the air gap are given.

9A and 9B, to promote substantially equal bias for the GMR elements, the GMR elements and segments are aligned with iso-lines of the bias magnetic field along an axis orthogonal to the reference direction. , that is, the dimensions can be adjusted or spaced apart depending on HyHy. As can be seen, in the exemplary embodiment, there is a left GMR element, a center GMR element and a right GMR element each having first and second segments. The left and right GMR elements experience different bias magnetic fields than the central elements as indicated by the isolines. The distance between the first and second segments of the left GMR element is ε _l and the length of the segment is δ _l . The distance between the segments of the central GMR element is ε _c and the length of the segment is δ _c . The distance between the first and second segments of the right GMR element is ε _r , and the length of the segment is δ _r . In the embodiment illustrated in Figure 9A, δ ₁ = δ _r = δ _c and ε ₁ = ε _r = ε _c . In the embodiment illustrated in Figure 9B, δ ₁ = δ _r ≠ δ _c and ε ₁ = ε _r ≠ ε _c because the center segment spacing and dimensions are different from the left and right segment spacing and dimensions. In embodiments, δ _c is selected such that HyHy at the bottom of the top yokes is the same on all left, center and right yokes. Additionally, HyHy at the bottom of the upper yokes is the same on all left, center and right yokes. In embodiments, the yokes are all the same size, with only the vertical spacing varying. The spacing is chosen so that the average HyHy value across the center yoke is the same on both sides. Figure 9c shows the same average bias on the above elements.

It will be appreciated that the lengths of the segments and the distances between the segments may be unique and configured to meet the needs of a particular application.

The arrangement of Figure 9b distributes substantially equal bias across the GMR bridge elements, for example. To maintain the same sensitivity, the center yokes and outer yokes should have the same resistance in the absence of any magnetic field. Since the square resistance of the stack forming the GMR elements is the same and the vertical length is fixed, a GMR segment with a zero magnetic field resistance adopts the GMR element width and/or is placed to the right in addition to the current elements. It can be applied by adding . These elements can be connected in series or parallel with the current elements. To this end, the sensitivity in Ω/Oe can be achieved to be substantially equal between each GMR element (when both the die and the magnet are perfectly aligned).

In another aspect, the bias magnet can be shaped to reduce sensitivity to the common mode magnetic field across X-axis misalignment of the sensor elements. As shown in Figure 10, for a rectangular magnet cross-section, the bias HyHy can change significantly when misalignment to the X axis occurs, as shown. Therefore, due to sensor element misalignment, the sensor may be sensitive to stray magnetic fields. The bias Hy is adjusted to the upper segment of the left element, the upper segment of the central element and the right element for the embodiment of FIG. 9B where the central element segments are spaced differently from the left and right element segments and are sized. Shown for the upper segment.

As shown in FIG. 10A, by changing the cross-section of the magnet in the You can become one, and you can approach the spirit. When X-axis misalignment occurs, the bias does not change significantly. Accordingly, the sensitivity to stray magnetic fields does not vary significantly over the range of X misalignment. In an ideal position, one is in the center, and as soon as there is a misalignment on Therefore, there is excellent suppression of misalignment because there is no change. In embodiments, Hy depends on the distance to the top/bottom ends of the magnet. The closer to the end, the higher Hy becomes. By reducing the height of the magnet at the sides, Hy is again increased by bringing these upper and lower ends closer to the yokes. This is how a function changes from going to 0 to increasing again.

As described herein, the term "magnetic field sensing element" is used to describe various types of electronic elements capable of sensing magnetic fields. The magnetic field sensing element may include, but is not limited to, a Hall Effect element, a magnetoresistive element, and/or a magnetotransistor. As is known, different types of Hall effect elements exist, such as planar Hall elements, vertical Hall elements and circular vertical Hall (CVH) elements. As also known, there are different types of magnetoresistive elements, such as semiconductor magnetoresistive elements such as indium antimonide (InSb), giant magnetoresistance (GMR) elements such as spin valves, anisotropic magnets, etc. There are resistive elements (AMR), tunneling magnetoresistance (TMR) elements, and magnetic tunnel junctions (MTJ). The magnetic field sensing element may be a single element, or alternatively may include two or more magnetic field sensing elements arranged in various configurations, e.g., a half bridge or a full bridge. there is. Depending on the type of device and other application requirements, the magnetic field sensing element may be made of a group IV semiconductor material such as silicon (Si) or germanium (Ge), or gallium-arsenide (GaAs) or, for example, indium antimonide (InSb). ) or indium compounds such as indium gallium arsenide (InGaAs). It can be a device made of a group III-V semiconductor material.

As is known, some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity substantially parallel to the substrate supporting the magnetic field sensing element, while others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity substantially parallel to the substrate supporting the magnetic field sensing element. There is a tendency to have the axis of maximum sensitivity substantially orthogonal to the substrate. In particular, planar Hall elements tend to have axes of sensitivity substantially orthogonal to the substrate, whereas metallic or metallic magnetoresistive elements (e.g. GMR, TMR, AMR) and vertical Hall elements tend to have axes of sensitivity substantially orthogonal to the substrate. There is a tendency to have substantially parallel axes of sensitivity.

As used herein, the term “magnetic field sensor” is generally used to describe a circuit that uses a magnetic field sensing element in combination with other circuits. Magnetic field sensors include, but are not limited to, an angle sensor that detects the angle of the direction of a magnetic field, a current sensor that detects a magnetic field generated by an electric current carried by a current-carrying conductor, and a magnetic sensor that detects the proximity of a ferromagnetic object. a switch, a rotational detector that senses passing ferromagnetic items, e.g. magnetic domains of a ring magnet or a ferromagnetic target (e.g. gear teeth) where a magnetic field sensor is used in combination with a back-bias or magnet, and It is used in a variety of applications, including magnetic field sensors that detect the magnetic field density of a magnetic field.

Figure 12 depicts an example computer 1200 capable of performing at least some of the processing described herein. The computer 1200 includes a processor 1202, volatile memory 1204, non-volatile memory 1206 (e.g., a hard disk), an output device 1207, and a graphical user interface (GUI) 1208 (e.g. For example, mouse, keyboard, display, etc.). The non-volatile memory 1206 stores computer instructions 1212, operating system 1216, and data 1218. In one embodiment, the computer instructions 1212 are executed by the processor 1202 external to volatile memory 1204. In one embodiment, article 1220 includes non-transitory computer-readable instructions.

The processing may be implemented in hardware, software, or a combination of the two. The processing may include, respectively, a processor, a storage medium or other article of manufacture readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and one or more output devices. It can be implemented as computer programs running on programmable computers/machines, including: Program code may be applied to data input using an input device to perform processing and generate output information.

The system may be implemented at least partially through a computer program product (e.g., in a machine-readable storage device) or through the operation of a data processing device (e.g., a programmable processor, computer, or multiple computers) for execution. Processing can be performed for control purposes. Each such program may be implemented in a high-level procedural or object-oriented programming language for communicating with a computer system. However, the programs may be implemented in assembly or machine language. The language may be a translated or interpreted language and may be used in any form, including stand-alone programs, modules, components, subroutines or other units suitable for use in a computational environment. The computer program may be used to run on a single computer or on multiple computers distributed across a site or multiple sites and connected by a communications network. A computer program is a general-purpose or dedicated programmable computer-readable storage medium or device (e.g., a CD-ROM, hard disk, or magnetic diskette) for configuration and operation when the storage medium or device is read by the computer. can be stored on Processing may also be implemented in a machine-readable storage medium, wherein, when executed, the computer program causes the computer to operate.

Processing may be implemented by one or more programmable processors executing one or more computer programs to perform the functions of the system. All or part of the system may be implemented as dedicated logic circuitry (e.g., field programmable gate array (FPGA) and/or application specific integrated circuit (ASIC)).

Although the foregoing has described exemplary embodiments of the present invention, other embodiments encompassing these concepts will be apparent to those skilled in the art. Embodiments of the present invention should not be understood as being limited to the embodiments described herein, but should be understood as being limited by the spirit and scope of the following claims.

All references mentioned herein are incorporated herein by reference in their entirety.

Elements of the embodiments described herein may be combined to implement other embodiments not specifically described above. Various elements described in the context of a single embodiment may also be provided separately or in any suitable sub-combination. Other embodiments not specifically described herein also fall within the scope of the following claims.

Claims (24)

In the sensor system,
A first magnetic field sensing element comprising first and second segments, the first and second segments being oriented in opposite directions to reduce sensitivity due to misalignment of the first and second segments. Located in locations that generate magnetic field bias;
A sensor system comprising a processing module that receives the output of the magnetic field sensing element. The sensor system of claim 1, wherein the misalignment is determined from the center of the magnetic field generated by the magnet. 2. The sensor system of claim 1, wherein the misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field. 2. The method of claim 1, wherein as misalignment increases, the first segment experiences a stronger magnetic field and the second segment experiences a weaker magnetic field, and the processing module reduces sensitivity due to misalignment of the first and second segments. and combining signals from the first and second segments to 2. The sensor system of claim 1, wherein the first magnetic field sensing element comprises a GMR that is separated into two parts. 6. The sensor system of claim 5, wherein the first and second magnetic field sensing elements are configured in a half-bridge configuration. 6. The sensor system of claim 5, further comprising third and fourth magnetic field sensing elements, wherein the first, second, third and fourth magnetic field sensing elements are configured in a bridge configuration. 8. The sensor system of claim 7, wherein the third magnetic field sensing element includes fifth and sixth segments and the fourth magnetic field sensing element includes seventh and eighth segments. 2. The sensor system of claim 1, wherein the first magnetic field sensing element comprises GMR elements. 2. The sensor system of claim 1, wherein the first magnetic field sensing element comprises TMR elements. Applying a first magnetic field sensing element having first and second segments, the first and second segments being in opposite directions to reduce sensitivity due to misalignment of the first and second segments. are located at locations that generate magnetic field bias;
and applying a processing module to receive the output of the magnetic field sensing element. 12. The method of claim 11, wherein the misalignment is determined from the center of the magnetic field generated by the magnet. 12. The method of claim 11, wherein the misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field. 12. The method of claim 11, wherein as misalignment increases, the first segment experiences a stronger magnetic field and the second segment experiences a weaker magnetic field, and the processing module reduces sensitivity due to misalignment of the first and second segments. and combining signals from the first and second segments to 12. The method of claim 11, wherein the first magnetic field sensing element comprises a GMR that is separated into two parts. 16. The method of claim 15, wherein the first and second magnetic field sensing elements are configured in a half-bridge configuration. 16. The method of claim 15, further comprising applying third and fourth magnetic field sensing elements, wherein the first, second, third and fourth magnetic field sensing elements are configured in a bridge configuration. 18. The method of claim 17, wherein the third magnetic field sensing element includes fifth and sixth segments and the fourth magnetic field sensing element includes seventh and eighth segments. 12. The method of claim 11, wherein the first magnetic field sensing element comprises GMR elements. 12. The method of claim 11, wherein the first magnetic field sensing element comprises TMR elements. In the sensor system,
Comprising magnetic field sensing means having first and second segments, the first and second segments generating a magnetic field bias in opposite directions to reduce sensitivity due to misalignment of the first and second segments. located in locations;
A sensor system comprising processing means for receiving the output of the magnetic field sensing means. 22. The sensor system of claim 21, wherein the misalignment is determined from the center of the magnetic field generated by the magnet. 22. The sensor system of claim 21, wherein the misalignment is due to the first and second segments being located at unequal distances from the center of the magnetic field. 22. The method of claim 21, wherein as misalignment increases, the first segment experiences a stronger magnetic field and the second segment experiences a weaker magnetic field, and the processing means reduces sensitivity due to misalignment of the first and second segments. and combining signals from the first and second segments to